Bidirectional Grammars Research Articles

Specifying and Verbalising Answer Set Programs in Controlled Natural Language

AbstractWe show how a bi-directional grammar can be used to specify and verbalise answer set programs in controlled natural language. We start from a program specification in controlled natural language and translate this specification automatically into an executable answer set program. The resulting answer set program can be modified following certain naming conventions and the revised version of the program can then be verbalised in the same subset of natural language that was used as specification language. The bi-directional grammar is parametrised for processing and generation, deals with referring expressions, and exploits symmetries in the data structure of the grammar rules whenever these grammar rules need to be duplicated. We demonstrate that verbalisation requires sentence planning in order to aggregate similar structures with the aim to improve the readability of the generated specification. Without modifications, the generated specification is always semantically equivalent to the original one; our bi-directional grammar is the first one that allows for semantic round-tripping in the context of controlled natural language processing.

Bidirectional Grammars for Machine-Code Decoding and Encoding

Binary analysis, which analyzes machine code, requires a decoder for converting bits into abstract syntax of machine instructions. Binary rewriting requires an encoder for converting instructions to bits. We propose a domain-specific language that enables the specification of both decoding and encoding in a single bidirectional grammar. With dependent types, a bigrammar enables the extraction of an executable decoder and encoder as well as a correctness proof showing their consistency. The bigrammar DSL is embedded in Coq with machine-checked proofs. We have used the bigrammar DSL to specify the decoding and encoding of subsets of the x86-32 and MIPS instruction sets. We have also extracted an executable decoder and encoder from the x86 bigrammar with competitive performance.

A Study on the Semantic Grammar as a Theory and Bi-directional Grammar as a Research Method

A Study on the Semantic Grammar as a Theory and Bi-directional Grammar as a Research Method

De l’ubiquité de l’ordre dans les premières grammaires catégorielles

Résumé Parmi les différences qui opposent les deux grands courants de grammaires formelles du XXe siècle, celles qui concernent le traitement de l’ordre des mots sont restées jusqu’à aujourd’hui peu traitées. Pourtant, les premières grammaires catégorielles (de 1935 à 1959) présentent une conception de l’ordre des mots qui tranche de celle mise en oeuvre dans le modèle trans-formationnel chomskien (1957) et leur originalité sur ce point mérite l’attention. La syntaxe d’Ajdukiewicz (1935), la grammaire bidirectionnelle de Bar-Hillel (1953) et le calcul syntaxique associatif de Lambek (1958, 1959) s’accordent en effet à gérer l’ordre en le faisant intervenir simultanément à tous les niveaux d’analyse. L’article précise le traitement de l’ordre des mots dans ces trois premières grammaires catégorielles et les compare entre elles de manière à dégager la portée qu’ont eu à un niveau conceptuel les modifications que ces différents auteurs ont introduites dans la notation de l’ordre.

An approach to intelligent speech production system

In the paper an intelligent speech production system is established by using language information processing technology. The concept of bi-directional grammar is proposed in Chinese language information processing and a corresponding Chinese characteristic network is completed. Correct text can be generated through grammar parsing and some additional rules. According to the generated text the system generates speech which has good quality in naturalness and intelligibility using Chinese Text-to-Speech Conversion System.

On the generating power of regularly controlled bidirectional grammars

RCB-grammars or regularly controlled bidirectional grammars are context-free grammars of which the rules can be used in a productive and in a reductive fashion. In addition, the application of these rules is controlled by a regular language. Several modes of derivation can be distinguished for this kind of grammar. In this paper the generating power of the derivation mode that uses right-occurrence rewriting (RO-mode) is determined. Furthermore, a new mode called RA is introduced, which is a better formalization of the intuitive idea of rightoccurrence rewriting than the RO-mode. The RO- and RA-mode have the same generating power, viz. the corresponding RCB-grammars both generate the recursively enumerable languages. Consequently, providing RCB/RO-grammars with a time bound results in a less powerful grammar model.

Time-bounded controlled bidirectional grammars

We study regularly controlled bidirectional (RCB) grammars from the viewpoint of time-bounded grammars. RCB-grammars are context-free grammars of which the rules can be used in a productive and in a reductive fashion, while the application of these rules is controlled by a regular language. Several modes of derivation can be distinguished for this kind of grammar. A time bound on such a grammar is a measure of its derivational complexity. For some families of time bounds and for some modes of derivation we establish closure properties and a normal form theorem. In addition parsing algorithms are given for some modes of derivation. We conclude with considering generalizations with respect to the family of control languages and the family of bounding functions..

Analysis and generation grammars

This paper describes the analysis and generation grammars for English and Japanese as they were employed in the KBMT-89 program. We discuss word order, coordination, subcategorization, morphological rules, rule ordering and bi-directional grammars.

Controlled bidirectional grammars

We investigate context-free grammars the rules of which can be used in a productive and in a reductive fashion, while the application of these rules is controlled by a regular language. We distinguish several modes of derivation for this kind of grammar. The resulting language families (properly) extend the family of context-free languages. We establish some closure properties of these language families and some grammatical transformations which yield a few normal forms for this type of grammar. Finally, we consider some special cases (viz. the context-free grammar is linear or left-linear), and generalizations, in particular, the use of arbitrary rather than regular control languages.

A direct proof of the equivalence of free categorial grammars and simple phrase structure grammars

In [2], Bar-Hillel, Gaifman, and Shamir prove that the simple phrase structure grammars (SPGs) defined by Chomsky are equivalent in a certain sense to Bar-Hillel's bidirectional categorial grammars (BCGs). On the other hand, Cohen [3] proves the equivalence of the latter ones to what the calls free categorial grammars (FCGs). They are closely related to Lambek's syntactic calculus which, in turn, is based on the idea due to Ajdukiewicz [1]. For the reasons which will be discussed in the last section, Cohen's proof seems to be at least incomplete. This paper yields a direct proof of the equivalence ofFCGs andSPGs.